Our studies will focus on understanding the nature of the actin-S-1 interaction in the presence and absence of ATP and the nature of the steps that occur in the actomyosin ATPase cycle. Efforts will also be made to understand the effect of the SH1 group on the catalytic nature of myosin Mg ion ATPase. The use of computer curve fitting in understanding the kinetic nature of different mechanistic models will be explored.